The gray wolf (Cams lupus), also known as the timber wolf, lives for less than 10 years in the wild but can live for up to 20 years in captivity. The gray wolf is the largest and most widespread species of the family Canidae. Other members the family Canidae include domestic dogs, hunting dogs, wolves, jackals, coyotes, and foxes. Gray wolves weigh between 100 and 110 pounds (45 and 55 kilograms) and resemble large domestic dogs, such as Alaskan malamutes. Gray wolves are strongly social animals and live in packs.

The gray wolf has suffered a significant decline in numbers in recent years. In many areas it has been hunted and killed because it is believed to pose a threat to humans and domesticated animals (cattle, sheep, and reindeer). The gray wolf is declining faster in North America than in Europe. In the United States, its range is limited to Alaska (10,000); Northern Minnesota (1,200); and a small population on Isle Royale, Michigan. There are perhaps a few packs in Wisconsin, northern Michigan, and the Rocky Mountain area. In Canada, gray wolves number approximately 15,000.

The gray wolf may soon suffer the fate of the red wolf (Canis rufus), which once flourished in the southeast and south central United States. The red wolf has been declared biologically extinct in the wild, now existing only in captivity and in a small re introduced population of captive-bred animals in North Carolina.